The use of high-power fiber-delivered lasers is increasing in popularity for a variety of applications such as materials processing, cutting, welding, and/or additive manufacturing. Fiber-coupled lasers include fiber-delivered lasers, disk lasers, diode lasers, direct diode lasers, diode-pumped solid state lasers, and lamp-pumped solid state lasers; fiber-delivered lasers are the most prevalent fiber-coupled laser source. In these systems, optical power is delivered from the laser to a work piece via an optical fiber, which typically includes a connector at the end. Intermediate fibers between the fiber-coupled laser and the work piece may also be employed, and these intermediate fibers also typically include connectors at both ends. These connectors are typically designed to precisely align the beam emerging from the fiber to maintain pointing of the output beam through the downstream optics and to facilitate multiple connection/disconnection cycles. Some problems that may arise in the fiber connectors can result in mechanical breakage of the fiber and/or destruction of the fiber as a result of excess heat which can cause damage to the internal environment in the fiber connector.
Some conventional industrial fiber-delivered lasers systems include simple two-wire circuits (sometimes referred to as “interlock circuits”) to monitor and indicate the presence of hazardous conditions in the fiber connector and/or the fiber cable. These simple circuits open when a hazard is recognized and shut the laser off. This interlock circuit is available if the cable is plugged into an appropriate receptacle. When the cable is properly mated to the receptacle, the two wires of the circuit are connected to one another and complete an interlock circuit. These same two wires run the length of the fiber cable and provide additional functionality by opening the circuit when subject to significant mechanical or thermal stress. Such stress may be due to a variety of fiber optic faults that cause burning, or by mechanical means such as being pinched by machinery. In these cases, the fragility of the wires allows them to sever which opens the circuit and safely shuts off the laser system. This system is fairly rigid, is only effective in the event of a catastrophic fault and does not enable resetting the laser system to a functional state.
Other conventional industrial fiber-delivered laser systems offer similar functionality and compatibility, but with the addition of a thermostatic switch located in series with the receptacle contacts. The thermostatic switch is located in the distal (output) head of the fiber cable and will open if the assembly reaches or exceeds some critical temperature that may damage the hardware. Once cooled, the thermostatic switch resets to allow operation of the laser to resume. However, such a system provides no information on the conditions inside the connector prior to a critical event causing shut-down and it does not allow users to manually set temperature thresholds.